An optical module of this type, known from FR-A-2 840 389, produces an infrared secondary lighting beam in a zone situated above the cut-off, by means of a diffuser fixed to the front face of the shield. The area of illumination of the secondary beam is situated essentially above the optical axis and is off-center with respect to this axis.
It is desirable to be able to perform other secondary functions, in particular a town lamp function or a DRL (Day Running Light) function in a headlight with an elliptical module with cut-off, for example a dipped headlight or a fog light. In the case of a town lamp or a DRL, the illumination grid, that is to say the zone illuminated on a screen situated at a given distance from the headlight and orthogonal to the optical axis, must be rectangular, centered on the optical axis between given limits.